Epoxybenzyl-terminated poly(arylene ether)s, method for preparation thereof, and curable compositions comprising same

ABSTRACT

An epoxybenzyl-terminated poly(arylene ether) has the structure R—W—R wherein W is a divalent poly(arylene ether) residue terminated with phenolic oxygen atoms, and R is an epoxybenzyl group, wherein each occurrence of R is the same or different. The epoxybenzyl-terminated poly(arylene ether) is formed by reacting a peroxide-containing reagent with a vinybenzyl-terminated poly(arylene ether). Also disclosed is a curable composition including the epoxybenzyl-terminated poly(arylene ether)s, a curing promoter, and, optionally, an auxiliary epoxy resin. The curable composition is useful for the preparation of composites, and in particular, composites used in manufacturing printed circuit boards.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. Nonprovisional application Ser.No. 13/224,050 filed Sep. 1, 2011, and is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

Epoxy resins are high performance materials used in a wide variety ofapplications including protective coatings, adhesives, electroniclaminates (such as those used in the fabrication of computer circuitboards), flooring and paving applications, glass fiber-reinforced pipes,and automotive parts (including leaf springs, pumps, and electricalcomponents). In their cured form, epoxy resins offer desirableproperties including good adhesion to other materials, excellentresistance to corrosion and chemicals, high tensile strength, and goodelectrical resistance. Two challenges associated with the use of epoxyresins are the brittleness of the cured epoxy resins and the need toheat many curable epoxy compositions enough to prepare, blend and shapethem, but not so much as to cure them prematurely.

Poly(arylene ether) resin is a type of plastic known for its excellentwater resistance, dimensional stability, and inherent flame retardancy.The addition of a poly(arylene ether) to an epoxy resin can reduce thebrittleness of the epoxy resin. For example, U.S. Pat. No. 4,912,172 toHallgren et al. describes a composition including a specific epoxy resinand a polyphenylene ether having a number average molecular weight of atleast about 12,000. However, relatively high temperatures are requiredto dissolve the polyphenylene ether in the epoxy resin, and prematurecuring of the epoxy resin is a risk at those high temperatures.

As another example, U.S. Pat. No. 5,834,565 to Tracy et al. describescompositions including an epoxy resin and a poly(arylene ether) having anumber average molecular weight less than 3,000. The low molecularweight poly(arylene ether) is easier to dissolve in the epoxy resin thanhigher molecular weight poly(arylene ether)s. However, the productsobtained on curing these compositions are not as tough as those preparedwith higher molecular weight poly(arylene ether)s.

The poly(arylene ether)s in the Hallgren and Tracy patents aremonofunctional, i.e. they possess one terminal phenolic group. U.S. Pat.No. 7,655,278 to Braidwood et al. describes compositions including anepoxy resin and a poly(arylene ether) having two terminal phenolicgroups. These compositions are easier to dissolve in the epoxy resin,and can advantageously be dissolved at 10 to 40° C.

Despite the higher solubility of bifunctional poly(arylene ether)s overmonofunctional poly(arylene ether)s and the known reactivity of phenolswith epoxy resins, both monofunctional and bifunctionalhydroxyl-terminated poly(arylene ether)s are relatively unreactive withepoxy resins at or near room temperature. The base catalyzed reaction ofthe terminal phenolic groups with epoxy resins is a slow reaction, whichcan require high temperatures and long times for complete curing. Thislower reactivity is problematic in diamine cured epoxy compositions. Ingeneral, stoichiometric or close to stoichiometric quantities ofdiamines are used to cure epoxy systems. The reactivity of epoxy resinswith diamine hardeners is significantly higher than with phenoliccompounds. With diamine hardeners, curing can occur under ambientconditions. Therefore, in ternary resin compositions comprisingpoly(arylene ether), epoxy resin, and diamine hardener, the epoxy resinreacts preferentially with the diamine hardener. There is little or noreaction of the epoxy resin with the poly(arylene ether), and there islittle or no incorporation of the poly(arylene ether) into the thermosetmatrix formed by reaction of the epoxy resin and the diamine hardener.The presence of unreacted poly(arylene ether) can have adverse effectson the cured epoxy resin composition, such as dual phase morphology,poor solvent resistance, and reduced impact strength.

One solution to the low reactivity of the phenolic end groups of thepoly(arylene ether) is to “up-stage” the poly(arylene ether). Up-stagingis the partial reaction of poly(arylene ether) with epoxy resin atelevated temperatures with or without a catalyst. Temperatures forup-staging can be as high as 250° C., and the reaction can take severalhours. Not every epoxy resin formulator has the equipment or time to doup-staging.

Another solution to the low reactivity of the phenolic end groups of thepoly(arylene ether) is to use poly(arylene ether) terminated withglycidyl ether groups. Poly(arylene ether) terminated with glycidylether groups are disclosed, for example, in U.S. Pat. No. 7,276,563 B2to Ishii et al., U.S. Patent Application Publication No. US2004/0214004A1 of Amagai et al., and C.-T. Su, K.-Y. Lin, T.-J. Lee, and M. Liang,European Polymer Journal, volume 46, pages 1488-1497, 2010. Howeverthese polymers are produced using a large (e.g., about 30-fold)stoichiometric excess of epichlorohydrin. The large excesses ofepichlorohydrin are used to minimize copolymerization of theepichlorohydrin with the poly(arylene ether) intermediate.Epichlorohydrin is not an environmentally friendly chemical. Thus itsuse in a manufacturing process, especially when it has to be used insuch large excesses beyond the amount that reacts, is undesirable fromindustrial hygiene and environmental viewpoints.

In addition to the above problems with the process for making prior artglycidyl ether terminated poly(arylene ether)s, poly(aryleneether)/epoxy compositions can have a two-phase polymer morphology, poorsolvent resistance due to solvent extraction of unreacted poly(aryleneether) that is not incorporated into the epoxy resin matrix, and poorimpact strength.

In view of the above problems associated with prior art poly(aryleneether) epoxy compositions, there remains a need for an epoxy-terminatedpoly(arylene ether) that is highly reactive in epoxy-containing curablecompositions, especially epoxy/hardener resin compositions, while at thesame time maintaining good solubility in the epoxy resin composition.There also remains a need for an epoxy-terminated poly(arylene ether)that does not require upstaging prior to use, and does not require theuse of epichlorohydrin in its manufacture. In terms of epoxy resincompositions, there remains a need for poly(aryleneether)/epoxy/compositions having a single phase polymer morphology,improved solvent resistance, and improved impact strength.

BRIEF DESCRIPTION OF THE INVENTION

One embodiment is a poly(arylene ether) having the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2.

Another embodiment is a poly(arylene ether) having the structure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

Another embodiment is a process of making the above poly(arylene ether),comprising reacting a peroxide-containing reagent with avinylbenzyl-terminated poly(arylene ether).

Another embodiment is a process of making a poly(arylene ether),comprising: reacting a hydroxyl-terminated poly(arylene ether) havingthe structure

with 4-vinylbenzyl chloride to form a vinylbenzyl-terminatedpoly(arylene ether) having the structure

and reacting the vinylbenzyl-terminated poly(arylene ether) with aperacid to form an epoxybenzyl-terminated poly(arylene ether) having thestructure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

Another embodiment is a curable composition comprising anepoxybenzyl-terminated poly(arylene ether) and a curing promoter.Another embodiment is a process of making the above curable composition,comprising mixing the epoxybenzyl-terminated poly(arylene ether) and thecuring promoter at about 10 to about 200° C. Another embodiment is acured composition obtained by curing the above curable composition.Another embodiment is an article comprising the cured composition.Another embodiment is a method of forming a composite, comprisingimpregnating a reinforcing structure with the curable composition;partially curing the curable composition to form a prepreg; andlaminating a plurality of prepregs. Other embodiments include acomposite formed by the method, and a printed circuit board comprisingthe composite.

Another embodiment is a curable composition comprising anepoxybenzyl-terminated poly(arylene ether), an auxiliary epoxy resin,and a curing promoter. Another embodiment is a process of making theabove curable composition, comprising mixing an epoxybenzyl-terminatedpoly(arylene ether), a curing promoter, and an auxiliary epoxy resin atabout 10 to about 200° C. Another embodiment is a cured compositionobtained by curing the above curable composition. Another embodiment isan article comprising the cured composition. Another embodiment is amethod of forming a composite, comprising impregnating a reinforcingstructure with the curable composition; partially curing the curablecomposition to form a prepreg; and laminating a plurality of prepregs.Other embodiments include a composite formed by the method, and aprinted circuit board comprising the composite.

These and other embodiments are described in detail below.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts scanning electron microscopy (SEM) images for curedm-phenylenediamine/epoxy/poly(arylene ether) compositions after tolueneetching; in image (a), the poly(arylene ether) is a hydroxyl-terminatedpoly(arylene ether); in image (b), the poly(arylene ether) is anepoxybenzyl-terminated poly(arylene ether).

FIG. 2 depicts SEM images for cured4,4′-diaminodiphenylmethane/epoxy/poly(arylene ether) compositions aftertoluene etching; in image (a), the poly(arylene ether) is ahydroxyl-terminated poly(arylene ether); in image (b), the poly(aryleneether) is an epoxybenzyl-terminated poly(arylene ether).

FIG. 3 is a graph of water absorption as a function of water immersiontime at 80° C. for comparative and inventive cured4,4′-diaminodiphenylmethane/epoxy compositions.

DETAILED DESCRIPTION OF THE INVENTION

In a search for poly(arylene ether)s that provide epoxy resincompositions having improved properties, the present inventors havedeveloped the epoxybenzyl-terminated poly(arylene ether)s describedherein. These poly(arylene ether)s provide several advantages when usedin epoxy resin compositions. Epoxybenzyl-terminated poly(arylene ether)sdo not need to be up-staged by partial reaction with epoxy resins priorto use in order to have sufficient cure rates. This simplifies their usefor the end-user, and eliminates the burdensome need for equipment tocarry out the up-staging. What's more, the epxoybenzyl-terminatedpoly(arylene ether)s are prepared without the use of epichlorohydrin,which is not an environmentally friendly chemical. Instead ofepichlorohydrin, which must be used in about a 30-fold molar excess,epoxybenzyl-terminated poly(arylene ether)s can be produced fromperacids in near stoichiometric amounts.

The epoxybenzyl-terminated poly(arylene ether)s of the present inventionprovide other advantages as well. Epoxy resin compositions comprisingepoxybenzyl-terminated poly(arylene ether)s exhibit increasedincorporation of the epoxybenzyl-terminated poly(arylene ether) into theepoxy matrix at or near room temperature relative to hydroxyl-terminatedpoly(arylene ether)s. The higher incorporation level results in severaladvantageous properties. With higher incorporation of theepoxybenzyl-terminated poly(arylene ether), a single phase polymermorphology is obtained. As demonstrated by the working examples, solventresistance and impact resistance are improved, and water adsorption isreduced, relative to existing epoxy resin compositions.

Thus, in some embodiments, a poly(arylene ether) has the structure

R—W—R,

wherein W is as divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group, wherein eachoccurrence of R is the same or different. As used herein, the term“epoxybenzyl group” means a benzyl group ring-substituted with one ortwo epoxy groups bonded directly to the aromatic ring. The epoxybenzylgroup can have the structure

wherein each occurrence of m is independently 1 or 2. Epoxybenzyl groupspecies include, for example,

and combinations thereof. In some embodiments the epoxybenzyl group Rhas the structure

The poly(arylene ether) residue W has the structure

wherein Q¹ and Q² are each independently selected from the groupconsisting of halogen, unsubstituted or substituted C₁-C₁₂ primary orsecondary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy,and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separatethe halogen and oxygen atoms; each occurrence of Q³ and Q⁴ isindependently selected from the group consisting of hydrogen, halogen,unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl,C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂halohydrocarbyloxy wherein at least two carbon atoms separate thehalogen and oxygen atoms; x and y are independently 0 to about 30,specifically 0 to about 20, more specifically 0 to about 15, still morespecifically 0 to about 10, even more specifically 0 to about 8,provided that the sum of x and y is at least 2, specifically at least 3,more specifically at least 4; and L has the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;z is 0 or 1; and Y has a structure selected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the groupconsisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶and R⁷ is independently selected from the group consisting of hydrogen,C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷collectively form a C₄-C₁₂ alkylene group.

As used herein, the term “hydrocarbyl”, whether used by itself, or as aprefix, suffix, or fragment of another term, refers to a residue havingan open valence that contains only carbon and hydrogen. The term“primary hydrocarbyl”, refers to a hydrocarbyl group having two or threehydrogen atoms bonded to the carbon atom with the open valence. The term“secondary hydrocarbyl” refers to a hydrocarbyl group having onehydrogen atom bonded to the carbon atom with the open valence. Thehydrocarbyl residue can be aliphatic or aromatic, straight-chain,cyclic, bicyclic, branched, saturated, or unsaturated. It can alsocontain combinations of aliphatic, aromatic, straight chain, cyclic,bicyclic, branched, saturated, and unsaturated hydrocarbon moieties.However, when the hydrocarbyl residue is described as substituted, itcan, optionally, contain heteroatoms over and above the carbon andhydrogen members of the substituent residue. Thus, when specificallydescribed as substituted, the hydrocarbyl residue can also contain oneor more heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon,or phosphorus. When substituted, the hydrocarbyl residue can contain theheteroatoms pendant to or within the backbone of the hydrocarbonresidue. As one example, Q¹ or Q² can be a di-n-butylaminomethyl groupformed by reaction of a methyl group of a 2,6-dimethylphenylene residuewith the di-n-butylamine component of an oxidative polymerizationcatalyst.

In some embodiments, the poly(arylene ether) can comprise a mixture ofpoly(arylene ether) species having different epoxybenzyl R groups. Forexample, the poly(arylene ether) can comprise a poly(arylene ether)species in which the epoxybenzyl R groups are both

a poly(arylene ether) species in which the epoxybenzyl R groups are both

and a poly(arylene ether) species in which the epoxybenzyl R groups are

In some embodiments, the poly(arylene ether) has the structure

wherein each occurrence of m is independently 1 or 2; Q¹ and Q² are eachindependently selected from the group consisting of halogen,unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl,C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂halohydrocarbyloxy wherein at least two carbon atoms separate thehalogen and oxygen atoms; each occurrence of Q³ and Q⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;x and y are independently 0 to about 30, provided that the sum of x andy is at least 2; and L has the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;z is 0 or 1; and Y has a structure selected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the groupconsisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶and R⁷ is independently selected from the group consisting of hydrogen,C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷collectively form a C₄-C₁₂ alkylene group.

In some embodiments, the poly(arylene ether) has the structure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

In some embodiments, a process of making a poly(arylene ether) havingthe structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2, comprises reacting aperoxide-containing reagent with a vinylbenzyl-terminated poly(aryleneether). The poly(arylene ether) residue W is as defined above.

Suitable peroxide-containing reagents include aliphatic or aromaticperacid perbenzoic acid, 3-chloroperbenzoic acid, monoperphthalic acid,p-methoxyperbenzoic acid, p-nitroperbenzoic acid, m-nitroperbenzoicacid, α-pernaphthoic acid, β-pernaphthoic acid, phenylperacetic acid,performic acid, peracetic acid, perpropionic acid, perbutyric acidperisovaleric acid, perheptanoic acid, and combinations thereof. In someembodiments, the peroxide-containing reagent is 3-chloroperbenzoic acid.

The vinylbenzyl-terminated poly(arylene ether) has the structure

S—W—S,

wherein the poly(arylene ether) residue W is as defined above, and S isa vinylbenzyl group having the structure

wherein each occurrence of S is the same or different, and eachoccurrence of m is independently 1 or 2.

In some embodiments, the vinylbenzyl-terminated poly(arylene ether) hasthe structure

wherein L, Q¹-Q⁴, m, x, and y are as defined above. In some embodiments,the vinylbenzyl-terminated poly(arylene ether) has the structure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2. Examples of thepreparation of vinylbenzyl-terminated poly(arylene ether)s can be foundin U.S. Patent Application Publication Nos. US 2005/0090624 A1 ofNorisue et al., and US 2009/0012331 A1 of Nakano et al.

In some embodiments, the vinylbenzyl-terminated poly(arylene ether) isreacted with a 0 to about 20 mole percent excess of peracid,specifically a 0 to about 15 mole percent excess, more specifically a 0to about 10 mole percent excess, and even more specifically a 0 to about5 mole percent excess of peracid, based on the moles of vinyl groupspresent in the vinylbenzyl-terminated poly(arylene ether). Dependingupon the specific peracid used, the reacting is conducted at atemperature of about −30 to about 50° C., specifically about −20 toabout 40° C., still more specifically about −15 to about 30° C., evenmore specifically about −10 to about 20° C., and yet more specificallyabout −5 to about 10° C. The reacting is conducted for about 1 to about20 hours, specifically about 2 to about 15 hours, more specificallyabout 3 to about 10 hours, and still more specifically about 5 to about8 hours. In some embodiments, the reacting is conducted neat (i.e. inthe absence of solvent), and in other embodiments, the reacting isconducted in the presence of a solvent. In some embodiments, the solventis a chlorinated hydrocarbon solvent, for example chloroform. In otherembodiments, the solvent is an aromatic hydrocarbon, for exampletoluene. In some embodiments, the acid generated by reaction of theperacid precipitates from solution, and can be separated by decantation,filtration, centrifugation, or any combination thereof. Solvent, ifutilized, can be removed from the vinylbenzyl-terminated poly(aryleneether) by distillation, optionally at reduced pressure.

When the peroxide-containing reagent is 3-chloroperbenzoic acid, themethod for the preparation of styrene oxide found in Organic Syntheses,Coll. Vol. 1, p. 404, 1941, and Vol. 8, p. 102, 1928, can be used. Thismethod is applicable when other peracids are used as well. Any desirablemodifications to the method when peracids other than 3-chloroperbenzoicacid are used will be readily apparent to the skilled person.

In some embodiments, the process further comprises reacting a hydroxylterminated poly(arylene ether) with a vinylbenzyl halide in the presenceof an alkali metal alkoxide to form the vinylbenzyl-terminatedpoly(arylene ether). The vinylbenzyl halide has the structure

wherein X is fluoride, chloride, bromide, or iodide, and m is 1 or 2. Insome embodiments, X is chloride. The vinylbenzyl halide can be3-vinylbenzyl chloride, 4-vinylbenzyl chloride, or a combination of3-vinylbenzyl chloride and 4-vinylbenzyl chloride. Commerciallyavailable vinylbenzyl chlorides include mixtures of 3-vinylbenzylchloride and 4-vinylbenzyl chloride, available from Dow Chemical Co, and4-vinylbenzyl chloride, available from Sigma-Aldrich.

Methods for preparing the vinylbenzyl halide will be readily apparent tothe skilled person in the art. For example, when m is 1, the vinylbenzylhalide can be prepared by halomethylation of styrene. When m is 2, thevinylbenzyl halide can be prepared by halomethylation of divinylbenzene.Halomethylation is described in Jerry March, Advanced Organic Chemistry,2nd Ed., McGraw-Hill, pp. 501-502, 1977. Both styrene and divinylbenzeneare commercially available. Divinylbenzene is available as a mixture ofo-divinylbenzene and p-divinylbenzene.

The hydroxyl-terminated poly(arylene ether) has the structure

H—W—H,

wherein the residue W is as defined above, and H represents a hydrogenatom. In some embodiments, the hydroxyl-terminated poly(arylene ether)is a bifunctional poly(arylene ether) having the structure

wherein Q¹ and Q² are identical within each phenylene ether unit andselected from the group consisting of halogen, unsubstituted orsubstituted C₁-C₁₂ hydrocarbyl provided that the hydrocarbyl group isnot tertiary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy,and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separatethe halogen and oxygen atoms; each occurrence of Q³ and Q⁴ isindependently selected from the group consisting of hydrogen, halogen,unsubstituted or substituted C₁-C₁₂ hydrocarbyl provided that thehydrocarbyl group is not tertiary hydrocarbyl, C₁-C₁₂ hydrocarbylthio,C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxy wherein at leasttwo carbon atoms separate the halogen and oxygen atoms; x and y areindependently 0 to about 30, specifically 0 to about 20, morespecifically 0 to about 15, still more specifically 0 to about 10, evenmore specifically 0 to about 8, provided that the sum of x and y is atleast 2, specifically at least 3, more specifically at least 4; and Lhas the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ hydrocarbyl provided that the hydrocarbyl group isnot tertiary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy,and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separatethe halogen and oxygen atoms; z is 0 or 1; and Y has a structureselected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the groupconsisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶and R⁷ is independently selected from the group consisting of hydrogen,C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷collectively form a C₄-C₁₂ alkylene group. In some embodiments, eachoccurrence of Q¹ and Q² is methyl, each occurrence of Q³ is hydrogen,each occurrence of Q⁴ is hydrogen or methyl, the sum of x and y is 2 toabout 15, each occurrence of R¹ and R² and R³ and R⁴ is independentlyhydrogen or methyl, and Y has the structure

wherein each occurrence of R⁶ and R⁷ is independently selected from thegroup consisting of hydrogen, C₁-C₁₂ hydrocarbyl, and C₁-C₆hydrocarbylene wherein R⁶ and R⁷ collectively form a C₄-C₁₂ alkylenegroup.

In the hydroxyl-terminated poly(arylene ether) structure above, thereare limitations on the variables x and y, which correspond to the numberof phenylene ether repeating units at two different places in thebifunctional poly(arylene ether) molecule. In the structure, x and y areindependently 0 to about 30, specifically 0 to about 20, morespecifically 0 to about 15, even more specifically 0 to about 10, yetmore specifically 0 to about 8. The sum of x and y is at least 2,specifically at least 3, more specifically at least 4. A particularpolyfunctional poly(arylene ether) resin can be analyzed by protonnuclear magnetic resonance spectroscopy (¹H NMR) to determine whetherthese limitations are met for the entire resin, on average.Specifically, ¹H NMR can distinguish between resonances for protonsassociated with internal and terminal phenylene ether groups, andinternal and terminal residues of a polyhydric phenol, as well as otherterminal residues. It is therefore possible to determine the averagenumber of phenylene ether repeat units per molecule, and the relativeabundance of internal and terminal residues derived from dihydricphenol.

In some embodiments, the hydroxyl-terminated poly(arylene ether) has thestructure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2. This hydroxyl-terminatedpoly(arylene ether) can be synthesized by oxidative copolymerization of2,6-xylenol and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane in thepresence of a catalyst comprising copper and di-n-butylamine.

Any of the above-described poly(arylene ether)s can contain minoramounts of structural units formed as a result of side reactionsoccurring during poly(arylene ether) synthesis or processing. Forexample, when a poly(arylene ether) is prepared by method comprisingoxidative polymerization of monomers comprising 2,6-dimethylphenol inthe presence of a secondary amine, thermal decomposition can generateminor amounts of the structural units

wherein the wavy bonds represent connections to the remainder of thepolyfunctional poly(arylene ether) molecule.

In some embodiments, a process of making a poly(arylene ether) comprisesreacting a hydroxyl-terminated poly(arylene ether) having the structure

with 4-vinylbenzyl chloride to form a vinylbenzyl-terminatedpoly(arylene ether) having the structure

and reacting the vinylbenzyl-terminated poly(arylene ether) with aperacid to form an epoxybenzyl-terminated poly(arylene ether) having thestructure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

In some embodiments, a curable composition comprises a poly(aryleneether) having the structure

R—W—R,

and a curing promoter, wherein W is a divalent poly(arylene ether)residue having terminal phenolic oxygen atoms, and R is an epoxybenzylgroup having the structure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. W is further defined above.

In some embodiments, the poly(arylene ether) has the structure

wherein L, Q¹-Q⁴, m, x, and y are as defined above. In some embodiments,the poly(arylene ether) has the structure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

The curable composition can comprise the poly(arylene ether) in anamount of about 1 to about 99.9 weight percent, specifically about 3 toabout 50 weight percent, more specifically about 5 to about 40 weightpercent, and still more specifically about 10 to about 30 weightpercent, based on the total weight of the curable composition.

In addition to the epoxybenzyl-terminated poly(arylene ether), thecurable composition also comprises a curing promoter. The term “curingpromoter” as used herein encompasses compounds whose roles in curingepoxy resins are variously described as those of a hardener, a hardeningaccelerator, a curing catalyst, and a curing co-catalyst, among others.Hardeners are coreactive curing agents. Hardeners react with the epoxygroups and/or the secondary hydroxyl groups of the epoxy resin. Suitablehardeners for epoxy resins are known in the art and include, forexample, amines, dicyandiamide, polyamides, amidoamines, Mannich bases,anhydrides, phenol-formaldehyde resins, carboxylic acid functionalpolyesters, polysulfides, polymercaptans, isocyanates, cyanate esters,and combinations thereof.

In some embodiments, the curing promoter comprises an amine. The aminecan be a polyamine, a tertiary amine, an amidine, and combinationsthereof. Examples of suitable polyamines include amine hardeners such asisophoronediamine, triethylenetetraamine, diethylenetriamine,aminoethylpiperazine, 1,2- and 1,3-diaminopropane,2,2-dimethylpropylenediamine, 1,4-diaminobutane, 1,6-diaminohexane,1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane,1,12-diaminododecane, 4-azaheptamethylenediamine,N,N′-bis(3-aminopropyl)butane-1,4-diamine, cyclohexanediamine,4,4′-methylenedianiline, diethyltoluenediamine, m-phenylenediamine,p-phenylenediamine, tetraethylenepentamine, 3-diethylaminopropylamine,3,3′-iminobispropylamine, 2,4-bis(p-aminobenzyl)aniline,tetraethylenepentamine, 3-diethylaminopropylamine, 2,2,4- and2,4,4-trimethylhexamethylenediamine, 1,2- and 1,3-diaminocyclohexane,1,4-diamino-3,6-diethylcyclohexane, 1,2-diamino-4-ethylcyclohexane,1,4-diamino-3,6-diethylcyclohexane, 1-cyclohexyl-3,4-diaminocyclohexane,4,4′-diaminondicyclohexylmethane, 4,4′-diaminodicyclohexylpropane,2,2-bis(4-aminocyclohexyl)propane,3,3′-dimethyl-4,4′-diaminodicyclohexylmethane,3-amino-1-cyclohexaneaminopropane, 1,3- and1,4-bis(aminomethyl)cyclohexane, m- and p-xylylenediamine, diethyltoluene diamines, and combinations thereof. In some embodiments, thecuring promoter comprises a hardener selected from the group consistingof m-phenylenediamine, 4,4′-diaminodiphenylmethane, and combinationsthereof.

Examples of suitable amine compounds further include tertiary aminehardening accelerators such as triethylamine, tributylamine,dimethylaniline, diethylaniline, benzyldimethylamine (BDMA)α-methylbenzyldimethylamine, N,N-dimethylaminoethanol,N,N-dimethylaminocresol, tri(N,N-dimethylaminomethyl)phenol, andcombinations thereof. Examples of suitable amine compounds furtherinclude imidazole hardening accelerators such as 2-methylimidazole,2-ethylimidazole, 2-laurylimidazole, 2-heptadecylimidazole,2-phenylimidazole, 4-methylimidazole, 4-ethylimidazole,4-laurylimidazole, 4-heptadecylimidazole, 2-phenyl-4-methylimidazole,2-phenyl-4-hydroxymethylimidazole, 2-ethyl-4-methylimidazole,2-ethyl-4-hydroxymethylimidazole, 1-cyanoethyl-4-methylimidazole,2-phenyl-4,5-dihydroxymethylimidazole, and combinations thereof.Examples of suitable amine compounds further include cyclic amidinehardening accelerators such as 4-diazabicyclo(2,2,2)octane (DABCO),diazabicycloundecene (DBU), 2-phenyl imidazoline, and combinationsthereof.

The curing promoter can comprise other amine compounds. Examples ofother suitable amine compounds include hardeners such as ketimines,which are the reaction products of ketones and primary aliphatic amines;polyetheramines, which are the reaction products of polyols derived fromethylene oxide or propylene oxide with amines; amine-terminatedpolyamides, prepared by the reaction of dimerized and trimerizedvegetable oil fatty acids with polyamines; amidoamines, imidazolines,and combinations thereof, for example the reaction product of diethylenetriamine and tall-oil fatty acid.

The curing promoter can comprise an anhydride hardener. Examples ofsuitable anhydrides include maleic anhydride (MA), phthalic anhydride(PA), hexahydro-o-phthalic anhydride (HEPA), tetrahydrophthalicanhydride (THPA), methyltetrahydrophthalic anhydride (MTHPA),methylhexahydrophthalic anhydride (MHHPA), nadic methyl anhydride(methyl himic anhydride, MHA), benzophenonetetracarboxylic diandydride(BTDA), tetrachlorophthalic anhydride (TCPA), pyromellitic dianhydride(PMDA), trimellitic anhydride (TMA), and combinations thereof.

The curing promoter can comprise a phenol-formaldehyde resin. Suitablephenol-formaldehyde resins include, for example, novolac type phenolresins, resole type phenol resins, aralkyl type phenol resins,dicyclopentadiene type phenol resins, terpene modified phenol resins,biphenyl type phenol resins, bisphenol type phenol resins,triphenylmethane type phenol resins, and combinations thereof.

The curing promoter can comprise a Mannich base. Examples of Mannichbases are the reaction products of an amine with phenol andformaldehyde, melamine-formaldehyde resins, urea-formaldehyde resins,and combinations thereof.

In addition to the tertiary amines listed above, the curing promoter cancomprise other hardening accelerators. Suitable examples of otherhardening accelerators are substituted ureas, for example3-phenyl-1,1-dimethyl urea; the reaction product of phenyl isocyanatewith dimethylamine; the reaction product of toluene diisocyanate withdimethylamine; quaternary phosphonium salts, such as tetraalkyl andalklytriphenylphosphonium halide; and combinations thereof.

The curing promoter can comprise a metal salt, for example a copper (II)or aluminum (III) salt of an aliphatic or aromatic carboxylic acid.Suitable examples of such salts include the copper (II), tin (II), andaluminum (III) salts of acetate, stearate, gluconate, citrate, benzoate,and like anions, as well as combinations thereof. The curing promotercan comprise a copper (II) or aluminum (III) β-diketonate. Suitableexamples of such metal diketonates include the copper (II) and aluminum(III) salts of acetylacetonate. The curing promoter can comprise aborontrifluoride-trialkylamine complex. An illustrative borontrifluoride-trialkylamine complex is boron trifluoride-trimethylaminecomplex.

The curing promoter can comprise a latent cationic cure catalyst. Latentcationic cure catalysts are used, for example, in UV-cured epoxy resincompositions. Latent cationic cure catalysts include, for example,diaryliodonium salts, phosphonic acid esters, sulfonic acid esters,carboxylic acid esters, phosphonic ylides, triarylsulfonium salts,benzylsulfonium salts, aryldiazonium salts, benzylpyridinium salts,benzylammonium salts, isoxazolium salts, and combinations thereof. Forexample, the curing promoter can be a latent cationic cure catalystcomprising a diaryliodonium salt having the structure

[(R¹⁰)(R¹¹)I]⁺X⁻

wherein R¹⁰ and R¹¹ are each independently a C₆-C₁₄ monovalent aromatichydrocarbon radical, optionally substituted with from 1 to 4 monovalentradicals selected from C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, nitro, and chloro;and wherein X⁻ is an anion. In some embodiments, the curing promoter isa latent cationic cure catalyst comprising a diaryliodonium salt havingthe structure

[(R¹⁰)(R¹¹)I]⁺SbF₆ ⁻

wherein R¹⁰ and R¹¹ are each independently a C₆-C₁₄ monovalent aromatichydrocarbon radical, optionally substituted with from 1 to 4 monovalentradicals selected from C₁-C₂₀ alkyl, C₁-C₂₀ alkoxy, nitro, and chloro.In some embodiments, the curing promoter is a latent cationic curecatalyst comprising 4-octyloxyphenyl phenyl iodoniumhexafluoroantimonate.

The amount of curing promoter will depend on the type of curingpromoter, as well as the identities and amounts of the other componentsof the curable composition. For example, when the curing promoter is alatent cationic cure catalyst, it can be used in an amount of about 0.1to about 10 parts by weight per 100 parts by weight total of thepoly(arylene ether) and the auxiliary epoxy resin (if present). Asanother example, when the curing promoter is a copper (II) or aluminum(III) beta-diketonate, it can be used in an amount of about 1 to 10parts by weight per 100 parts by weight of the poly(arylene ether) andthe auxiliary epoxy resin (if present). As yet another example, when thecuring promoter is an amine hardener, it can be used in an amount ofabout 2 to about 40 parts by weight, per 100 parts by weight of thepoly(arylene ether) and the auxiliary epoxy resin (if present). As yetanother example, when the curing promoter is an imidazole hardeningaccelerator, it can be used in an amount of about 0.01 to about 5 partsby weight, per 100 parts by weight of the poly(arylene ether) and theauxiliary epoxy resin (if present).

In some embodiments, the curing promoter comprises a hardener, and thecurable composition comprises the curing promoter in an amount of about0.1 to about 50 weight percent, specifically about 0.5 to about 30weight percent, more specifically about 1 to about 20 weight percent,and still more specifically, about 2 to about 10 weight percent, basedon the weight of the curable composition.

When the curing promoter comprises a hardener, its amount can bespecified in terms of equivalents relative to total epoxy equivalents.For example, when the curing promoter comprises an amine hardener, thepoly(arylene ether), the curing promoter, and auxiliary epoxy resinprovide a ratio of total epoxy equivalents to total amine equivalents ofabout 1:1 to about 1.3:1, specifically about 1.1:1 to about 1.2:1, andstill more specifically about 1.1:1 to about 1.2:1.

In some embodiments, the curable composition further comprises anauxiliary epoxy resin, in addition to the poly(arylene ether) and curingpromoter. The auxiliary resin is different than theepoxybenzyl-terminated poly(arylene ether). Suitable auxiliary epoxyresins include those described by the structure

wherein A is a an organic or inorganic radical of valence n, Y is oxygenor nitrogen, r is 1 or 2 and consistent with the valence of X, R ishydrogen or methyl, s is 1 to about 1000, specifically 1 to 8, morespecifically 2 or 3 or 4.

Suitable classes of auxiliary epoxy resins include, for example,aliphatic epoxy resins, cycloaliphatic epoxy resins, bisphenol A epoxyresins, bisphenol-F epoxy resins, phenol novolac epoxy resins,cresol-novolac epoxy resins, biphenyl epoxy resins, polyfunctional epoxyresins, naphthalene epoxy resins, divinylbenzene dioxide,2-glycidylphenylglycidyl ether, dicyclopentadiene-type epoxy resins,multi-aromatic resin type epoxy resins, and combinations thereof.

Suitable auxiliary epoxy resins include those having the followingstructures

wherein each occurrence of R is independently hydrogen or methyl; eachoccurrence of M is independently C₁-C₁₈ hydrocarbylene optionallyfurther comprising a member or members selected from oxirane, carboxy,carboxamide, ketone, aldehyde, alcohol, halogen, nitrile; eachoccurrence of X is independently hydrogen, chloro, fluoro, bromo, C₁-C₁₈hydrocarbyl optionally further comprising a member or members selectedfrom carboxy, carboxamide, ketone, aldehyde, alcohol, halogen, andnitrile; each occurrence of B is independently a carbon-carbon singlebond, C₁-C₁₈ hydrocarbyl, C₁-C₁₂ hydrocarbyloxy, C₁-C₁₂ hydrocarbylthio,carbonyl, sulfide, sulfonyl, sulfonyl, phosphoryl, silane, or suchgroups further comprising a member or members selected fromcarboxyalkyl, carboxamide, ketone, aldehyde, alcohol, halogen, andnitrile; s is 1 to about 20; and each occurrence of p and q isindependently 0 to about 20.

Suitable auxiliary epoxy resins include those produced by the reactionof epichlorohydrin or epibromohydrin with a phenolic compound. Suitablephenolic compounds include resorcinol, catechol, hydroquinone,2,6-dihydroxynaphthalene, 2,7-dihydroxynapthalene,2-(diphenylphosphoryl)hydroquinone, bis(2,6-dimethylphenol)2,2′-biphenol, 4,4-biphenol, 2,2′,6,6′-tetramethylbiphenol,2,2′,3,3′,6,6′-hexamethylbiphenol,3,3′,5,5′-tetrabromo-2,2′6,6′-tetramethylbiphenol,3,3′-dibromo-2,2′,6,6′-tetramethylbiphenol,2,2′,6,6′-tetramethyl-3,3′,5-tribromobiphenol,4,4′-isopropylidenediphenol (bisphenol A),4,4′-isopropylidenebis(2,6-dibromophenol) (tetrabromobisphenol A),4,4′-isopropylidenebis(2,6-dimethylphenol) (teramethylbisphenol A),4,4′-isopropylidenebis(2-methylphenol),4,4′-isopropylidenebis(2-allylphenol),4,4′-(1,3-phenylenediisopropylidene)bisphenol (bisphenol M),4,4′-isopropylidenebis(3-phenylphenol),4,4′-(1,4-phenylenediisoproylidene)bisphenol (bisphenol P),4,4′-ethylidenediphenol (bisphenol E), 4,4′-oxydiphenol,4,4′-thiodiphenol, 4,4′-thiobis(2,6-dimethylphenol),4,4′-sulfonyldiphenol, 4,4′-sulfonylbis(2,6-dimethylphenol)4,4′-sulfinyldiphenol, 4,4′-hexafluoroisoproylidene)bisphenol (BisphenolAF), 4,4′-(1-phenylethylidene)bisphenol (Bisphenol AP),bis(4-hydroxyphenyl)-2,2-dichloroethylene (Bisphenol C),bis(4-hydroxyphenyl)methane (Bisphenol-F),bis(2,6-dimethyl-4-hydroxyphenyl)methane,4,4′-(cyclopentylidene)diphenol, 4,4′-(cyclohexylidene)diphenol(Bisphenol Z), 4,4′-(cyclododecylidene)diphenol4,4′-bicyclo[2.2.1]heptylidene)diphenol,4,4′-(9H-fluorene-9,9-diyl)diphenol,3,3-bis(4-hydroxyphenyl)isobenzofuran-1(3H)-one,1-(4-hydroxyphenyl)-3,3-dimethyl-2,3-dihydro-1H-inden-5-ol,1-(4-hydroxy-3,5-dimethylphenyl)-1,3,3,4,6-pentamethyl-2,3-dihydro-1H-inden-5-ol,3,3,3′,3′-tetramethyl-2,2′,3,3′-tetrahydro-1,1′-spirobi[indene]-5,6′-diol(spirobiindane), dihydroxybenzophenone (bisphenol K),tris(4-hydroxyphenyl)methane, tris(4-hydroxyphenyl)ethane,tris(4-hydroxyphenyl)propane, tris(4-hydroxyphenyl)butane,tris(3-methyl-4-hydroxyphenyl)methane,tris(3,5-dimethyl-4-hydroxyphenyl)methane,tetrakis(4-hydroxyphenyl)ethane,tetrakis(3,5-dimethyl-4-hydroxyphenyl)ethane,bis(4-hydroxyphenyl)phenylphosphine oxide,dicyclopentadienylbis(2,6-dimethyl phenol), dicyclopentadienylbis(2-methylphenol), dicyclopentadienyl bisphenol, and combinationsthereof. In some embodiments, the epoxy resin comprises a bisphenol Adiglycidyl ether epoxy resin (for example, a diglycidyl ether of2,2-bis(4-hydroxyphenyl)propane).

Other suitable auxiliary epoxy resins include N-glycidyl phthalimide,N-glycidyl tetrahydrophthalimide, phenyl glycidyl ether, p-butylphenylglycidyl ether, styrene oxide, neohexene oxide, ethylene glycoldiglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycoldiglycidyl ether, polypropylene glycol diglycidyl ether,tetramethyleneglycol diglycidyl ether, polytetramethylene glycoldiglycidyl ether, bisphenol A-type epoxy compounds, bisphenol S-typeepoxy compounds, resorcinol-type epoxy compounds, phenol novolac-typeepoxy compounds, ortho-cresol novolac-type epoxy compounds, adipic aciddiglycidyl ester, sebacic acid diglycidyl ester, and phthalic aciddiglycidyl ester. Also included are the glycidyl ethers of phenolicresins such as the glycidyl ethers of phenol-formaldehyde novolac, alkylsubstituted phenol-formaldehyde resins including cresol-formaldehydenovolac, t-butylphenol-formaldehyde novolac,sec-butylphenol-formaldehyde novolac, tert-octylphenol-formaldehydenovolac, cumylphenol-formaldehyde novolac, decylphenol-formaldehydenovolac. Other useful auxiliary epoxy resins are the glycidyl ethers ofbromophenol-formaldehyde novolac, chlorophenol-formaldehyde novolac,phenol-bis(hydroxymethyl)benzene novolac,phenol-bis(hydroxymethylbiphenyl) novolac, phenol-hydroxybenzaldehydenovolac, phenol-dicylcopentadiene novolac, naphthol-formaldehydenovolac, naphthol-bis(hydroxymethyl)benzene novolac,naphthol-bis(hydroxymethylbiphenyl) novolac,naphthol-hydroxybenzaldehyde novolac, naphthol-dicylcopentadienenovolac, and combinations thereof.

Also suitable as auxiliary epoxy resins are the polyglycidyl ethers ofpolyhydric aliphatic alcohols. Examples of such polyhydric aliphaticalcohols that can be mentioned are 1,4-butanediol, 1,6-hexanediol,polyalkylene glycols, glycerol, trimethylolpropane,2,2-bis(4-hydroxy-cyclohexyl)propane, pentaerythritol, and combinationsthereof.

Further suitable auxiliary epoxy resins are polyglycidyl esters whichare obtained by reacting epichlorohydrin or similar epoxy compounds withan aliphatic, cycloaliphatic, or aromatic polycarboxylic acid, such asoxalic acid, adipic acid, glutaric acid, phthalic, isophthalic,terephthalic, tetrahydrophthalic or hexahydrophthalic acid,2,6-naphthalenedicarboxylic acid, and dimerized fatty acids. Specificexamples are diglycidyl terephthalate and diglycidyl hexahydrophthalate.Moreover, polyepoxide compounds which contain the epoxide groups inrandom distribution over the polymer chain, and which can be prepared byemulsion copolymerization using olefinically unsaturated compounds thatcontain these epoxide groups, such as, for example, glycidyl esters ofacrylic or methacrylic acid, can be employed with advantage in somecases.

Examples of further auxiliary epoxy resins that can be used are thosebased on heterocyclic ring systems, for example hydantoin epoxy resins,triglycidyl isocyanurate and its oligomers, triglycidyl-p-aminophenol,triglycidyl-p-aminodiphenyl ether, tetraglycidyldiaminodiphenylmethane,tetraglycidyldiaminodiphenyl ether, tetrakis(4-glycidyloxyphenyl)ethane,urazole epoxides, uracil epoxides, and oxazolidinone-modified epoxyresins. Other examples are polyepoxides based on aromatic amines, suchas aniline, for example N,N-diglycidylaniline, diaminodiphenylmethane,N,N-dimethylaminodiphenylmethane or N,N-dimethylaminodiphenyl sulfone;and cycloaliphatic epoxy resins such as3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexane carboxylate,4,4′-(1,2-epoxyethyl)biphenyl, 4,4′-di(1,2-epoxyethyl)diphenyl ether,and bis(2,3-epoxycyclopentyl)ether.

Oxazolidinone-modified epoxy resins are also suitable. Compounds of thiskind are disclosed in, for example, Angew. Makromol. Chem., vol. 44,(1975), pages 151-163, and U.S. Pat. No. 3,334,110 to Schramm. Aspecific example is the reaction product of bisphenol A diglycidyl etherwith diphenylmethane diisocyanate in the presence of an appropriateaccelerator.

Epoxy resin oligomers prepared by condensation of an epoxy resin with aphenol such as a bisphenol are also suitable. A typical example is thecondensation of bisphenol A with a bisphenol A diglycidyl ether toproduce an oligomeric diglycidyl ether. In another example a phenoldissimilar to the one used to derive the epoxy resin can be used. Forexample tetrabromobisphenol A can be condensed with bisphenol Adiglycidyl ether to produce an oligomeric diglycidyl ether containinghalogens.

Further suitable auxiliary epoxy resins as well as curing promoters aredescribed in Henry Lee and Kris Neville, “Handbook of Epoxy Resins”McGraw-Hill Book Company, 1967, and Henry Lee “Epoxy Resins”, AmericanChemical Society, 1970.

The auxiliary epoxy resin can be a solid at room temperature. Thus, insome embodiments, the epoxy resin has a softening point of 25° C. toabout 150° C. Softening points can be determined according to ASTME28-99 (2004), “Standard Test Methods for Softening Point of ResinsDerived from Naval Stores by Ring-and-Ball Apparatus”. The auxiliaryepoxy resin can be a liquid or a softened solid at room temperature.Thus, in some embodiments, the auxiliary epoxy resin has a softeningpoint less than 25° C.

In some embodiments, the curable composition comprises the auxiliaryepoxy resin in an amount of 0 to about 99 weight percent, specificallyabout 1 to about 99 weight percent, more specifically about 10 to about90 weight percent, still more specifically about 40 to about 85 weightpercent, and even more specifically about 50 to about 80 weight percent,based on the total weight of the curable composition.

In some embodiments, the curable composition comprises about 1 to about99.9 weight percent of the epoxybenzyl-terminated poly(arylene ether)and about 0.1 to 50 weight percent of the curing promoter, based on thetotal weight of the curable composition. In other embodiments, thecurable composition comprises about 1 to about 99.9 weight percent ofthe epoxybenzyl-terminated poly(arylene ether), about 0.1 to 50 weightpercent of the curing promoter, and about 1 to about 99 weight percentof the auxiliary epoxy resin, based on the total weight of the curablecomposition.

In addition to the poly(arylene ether), the curing promoter, and theauxiliary epoxy resin, the curable composition can, optionally, comprisea solvent. The solvent can have an atmospheric boiling point of about 50to about 250° C. A boiling point in this range facilitates removal ofsolvent from the curable composition while minimizing or eliminating theeffects of bubbling during solvent removal. The solvent promotesformation of a homogeneous resin mixture, which in turn provides wet-outand adhesion to the glass reinforcement of the prepreg. When solvent ispresent, the presence of the poly(arylene ether) increases the viscosityof the curable composition, reducing the flow of the curable compositionat elevated temperatures, which is desirable for a lamination process.

The solvent can be, for example, a C₃-C₈ ketone, a C₃-C₈N,N-dialkylamide, a C₄-C₁₆ dialkyl ether, a C₆-C₁₂ aromatic hydrocarbon,a C₁-C₃ chlorinated hydrocarbon, a C₃-C₆ alkyl alkanoate, a C₂-C₆ alkylcyanide, or a combination thereof. The carbon number ranges refer to thetotal number of carbon atoms in the solvent molecule. For example, aC₄-C₁₆ dialkyl ether has 4 to 16 total carbon atoms, and the two alkylgroups can be the same or different. As other examples, the 3 to 8carbon atoms in the “N,N-dialkylamide” include the carbon atom in theamide group, and the 2 to 6 carbons in the “C₂-C₆ alkyl cyanides”include the carbon atom in the cyanide group. Specific ketone solventsinclude, for example, acetone, methyl ethyl ketone, methyl isobutylketone, and combinations thereof. Specific C₄-C₈ N,N-dialkylamidesolvents include, for example, dimethylformamide, dimethylacetamide,N-methyl-2-pyrrolidone (Chemical Abstracts Service Registry No.872-50-4), and combinations thereof. Specific dialkyl ether solventsinclude, for example, tetrahydrofuran, ethylene glycol monomethylether,dioxane, and combinations thereof. In some embodiments, the C₄-C₁₆dialkyl ethers include cyclic ethers such as tetrahydrofuran anddioxane. In some embodiments, the C₄-C₁₆ dialkyl ethers are noncyclic.The dialkyl ether can, optionally, further include one or more etheroxygen atoms within the alkyl groups and one or more hydroxy groupsubstituents on the alkyl groups. The aromatic hydrocarbon solvent cancomprise an ethylenically unsaturated solvent. Specific aromatichydrocarbon solvents include, for example, benzene, toluene, xylenes,styrene, divinylbenzenes, and combinations thereof. The aromatichydrocarbon solvent is preferably non-halogenated. That is, it does notinclude any fluorine, chlorine, bromine, or iodine atoms. Specific C₃-C₆alkyl alkanoates include, for example, methyl acetate, ethyl acetate,methyl propionate, ethyl propionate, and combinations thereof. SpecificC₂-C₆ alkyl cyanides include, for example, acetonitrile, propionitrile,butyronitrile, and combinations thereof. In some embodiments, thesolvent is acetone. In some embodiments, the solvent is methyl ethylketone. In some embodiments, the solvent is methyl isobutyl ketone. Insome embodiments, the solvent is N-methyl-2-pyrrolidone. In someembodiments, the solvent is dimethylformamide. In some embodiments, thesolvent is ethylene glycol monomethyl ether.

When a solvent is utilized, the curable composition can comprise about 2to about 100 parts by weight of the solvent, based on 100 parts byweight total of the poly(arylene ether), the curing promoter, and theauxiliary epoxy resin. Specifically, the solvent amount can be about 5to about 80 parts by weight, more specifically about 10 to about 60parts by weight, and even more specifically about 20 to about 40 partsby weight, based on 100 parts by weight total of the poly(aryleneether), the curing promoter, and the auxiliary epoxy resin. The solventcan be chosen, in part, to adjust the viscosity of the curablecomposition. Thus, the solvent amount can depend on variables includingthe type and amount of poly(arylene ether), the type and amount ofcuring promoter, the type and amount of auxiliary epoxy resin, and theprocessing temperature used for impregnation of the reinforcingstructure with the curable composition.

The curable composition can further comprise an inorganic filler.Suitable inorganic fillers include, for example, alumina, silica(including fused silica and crystalline silica), boron nitride(including spherical boron nitride), aluminum nitride, silicon nitride,magnesia, magnesium silicate, glass fibers, glass mat, and combinationsthereof. Suitable glass fibers include those based on E, A, C, ECR, R,S, D, and NE glasses, as well as quartz. The glass fiber can have adiameter of about 2 to about 30 micrometers, specifically about 5 toabout 25 micrometers, more specifically about 5 to about 15 micrometers.The length of the glass fibers before compounding can be about 2 toabout 7 millimeters, specifically about 1.5 to about 5 millimeters.Alternatively, longer glass fibers or continuous glass fibers can beused. The glass fiber can, optionally, include an adhesion promoter toimprove its compatibility with the poly(arylene ether), the auxiliaryepoxy resin, or both. Adhesion promoters include chromium complexes,silanes, titanates, zircon-aluminates, propylene maleic anhydridecopolymers, reactive cellulose esters and the like. Suitable glass fiberis commercially available from suppliers including, for example, OwensCorning, Nippon Electric Glass, PPG, and Johns Manville.

When an inorganic filler is utilized, the curable composition cancomprise about 2 to about 900 parts by weight of inorganic filler, basedon 100 parts by weight total of the poly(arylene ether), the curingpromoter, and the auxiliary epoxy resin. In some embodiments, thecurable composition comprises about 100 to about 900 parts by weightinorganic filler, specifically about 200 to about 800 parts by weightinorganic filler, and more specifically about 300 to about 700 parts byweight inorganic filler, based on 100 parts by weight total poly(aryleneether), curing promoter, and auxiliary epoxy resin. In some embodiments,the curable composition comprises less than 50 parts by weight inorganicfiller, or less than 30 parts by weight inorganic filler, or less than10 parts by weight inorganic filler, based of 100 parts by weight totalof the poly(arylene ether), the curing promoter, and the auxiliary epoxyresin. In some embodiments, the curable composition can be substantiallyfree of inorganic filler (that is, the composition can comprises lessthan 0.1 weight percent of added inorganic filler, based 100 parts byweight of the poly(arylene ether), the curing promoter, and theauxiliary epoxy resin).

The curable composition can, optionally, further comprise one or moreadditives. Suitable additives include, for example, solvents, dyes,pigments, colorants, antioxidants, heat stabilizers, light stabilizers,plasticizers, lubricants, flow modifiers, drip retardants, flameretardants, antiblocking agents, antistatic agents, flow-promotingagents, processing aids, substrate adhesion agents, mold release agents,toughening agents, low-profile additives, stress-relief additives, andcombinations thereof.

In some embodiments, a method of forming a curable composition comprisesmixing a poly(arylene ether), a curing promoter, and optionally, anauxiliary epoxy resin, wherein the poly(arylene ether) has the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter, and the auxiliary epoxy resin are further describedabove. The mixing is advantageously conducted at a temperature of about10 to about 200° C., specifically about 20 to about 180° C., morespecifically about 40 to about 160° C., still more specifically about 50to about 150° C., and even more specifically about 60 to about 120° C.,and yet more specifically at about 70 to about 110° C.

In some embodiments, a cured composition is obtained by curing a curablecomposition comprising a poly(arylene ether), a curing promoter, andoptionally, an auxiliary epoxy resin, wherein the poly(arylene ether)has the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter, and the auxiliary epoxy resin are further describedabove.

The cured composition exhibits several advantageous properties. In someembodiments, the cured composition exhibits excellent solventresistance, for example resistance to toluene. In some embodiments, thesurface of a microtomed slice of the cured composition is not etched byexposure to toluene at 23° C. for 15 seconds, as viewed under 3,000×magnification by scanning electron microscopy

In some embodiments, the cured composition exhibits a single glasstransition temperature. The presence of a single glass transitiontemperature, as opposed to two or more glass transition temperatures,indicates that the epoxybenzyl-terminated poly(arylene ether) iscovalently bound to the epoxy resin matrix of the cured composition. Inother words, the epoxybenzyl-terminated poly(arylene ether) does notexist as a separate phase within the epoxy resin matrix. Depending uponthe type and relative amounts of poly(arylene ether), curing promoter,and auxiliary epoxy resin, the glass transition temperature of the curedcomposition can be about 100 to about 250° C., specifically about 120 toabout 230° C., and more specifically about 140 to about 210° C. In someembodiments, the glass transition temperature is about 150 to about 200°C.

The composition can exhibit good impact strength. In some embodiments,the composition exhibits an unnotched Izod impact strength of at least400 joules per meter, specifically about 400 to about 600 joules permeter, more specifically about 450 to about 550 joules per meter, andstill more specifically about 480 to about 520 joules per meter, asmeasured at 23° C. with a hammer energy of 2 foot-pounds in accordancewith ASTM D 4812-06.

In some embodiments, the cured composition can exhibit a dielectricconstant of about 2.8 to about 3.2, specifically about 2.9 to about 3.1,and more specifically, about 3.00 to about 3.06, as measured at 1,000megahertz in accordance with IPC-TM-650 2.5.5.9.

In some embodiments, the cured composition can exhibit a loss tangent ofabout 0.011 to about 0.017, specifically about 0.012 to about 0.016, andmore specifically about 0.013 to about 0.015, as measured at 1,000megahertz in accordance with IPC-TM-650 2.5.5.9.

In some embodiments, the cured composition can exhibit a waterabsorption of less than or equal to 5 weight percent, specifically lessthan or equal to 4 weight percent, more specifically less than or equalto 3 weight percent, and still more specifically less than or equal to 2weight percent, measured after immersion in deionized water at 80° C.for 250 hours.

The cured composition can also exhibit a number of advantageousproperties simultaneously. In some embodiments, the cured compositioncan exhibit at least one of the following properties: a glass transitiontemperature of about 150 to about 200° C.; a dielectric constant ofabout 2.8 to about 3.2, as measured at 1,000 megahertz in accordancewith IPC-TM-650 2.5.5.9; a loss tangent of about 0.011 to about 0.017,as measured at 1,000 megahertz, in accordance with IPC-TM-650 2.5.5.9;and a water adsorption of less than or equal to 2 weight percent,measured after immersion in deionized water at 80° C. for 250 hours. Insome embodiments, the cured composition can exhibit at least two of theproperties. In other embodiments, the cured composition can exhibit atleast three of the properties.

The advantageous properties of the cured composition make it ideallysuited for forming certain articles. Thus, in some embodiments, anarticle comprises the cured composition obtained by curing a curablecomposition comprising a poly(arylene ether), a curing promoter, andoptionally, an auxiliary epoxy resin, wherein the poly(arylene ether)has the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter and the auxiliary epoxy resin are further describedabove.

The curable composition is particularly well suited for use in formingcomposites used for printed circuit boards. Methods of formingcomposites for use in printed circuit boards are known in the art andare described in, for example, U.S. Pat. No. 5,622,588 to Weber, U.S.Pat. No. 5,582,872 to Prinz, and U.S. Pat. No. 7,655,278 to Braidwood.

Thus, in some embodiments, a method of forming a composite comprisesimpregnating a reinforcing structure with a curable composition;partially curing the curable composition to form a prepreg; andlaminating a plurality of prepregs; wherein the curable compositioncomprises a poly(arylene ether), a curing promoter, and optionally, anauxiliary epoxy resin; and wherein the poly(arylene ether) has thestructure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter, and the auxiliary epoxy resin are further describedabove.

Reinforcing structures suitable for prepreg formation are known in theart. Suitable reinforcing structures include reinforcing fabrics.Reinforcing fabrics include those having complex architectures,including two or three-dimensional braided, knitted, woven, and filamentwound. The curable composition is capable of permeating such complexreinforcing structures. The reinforcing structure can comprise fibers ofmaterials known for the reinforcement of plastics material, for examplefibers of carbon, glass, metal, and aromatic polyamides. Suitablereinforcing structures are described, for example, in Anonymous (HexcelCorporation), “Prepreg Technology”, March 2005, Publication No. FGU017b; Anonymous (Hexcel Corporation), “Advanced Fibre Reinforced MatrixProducts for Direct Processes”, June 2005, Publication No. ITA 272; andBob Griffiths, “Farnborough Airshow Report 2006”, CompositesWorld.com,September 2006. The weight and thickness of the reinforcing structureare chosen according to the intended use of the composite using criteriawell known to those skilled in the production of fiber reinforced resincomposites. The reinforced structure can contain various finishessuitable for the epoxy matrix.

The method of forming the composite comprises partially curing thecurable composition after the reinforcing structure has been impregnatedwith it. Partial curing is curing sufficient to reduce or eliminate thewetness and tackiness of the curable composition but not so great as tofully cure the composition. The resin in a prepreg is customarily in thepartially cured state, and those skilled in the thermoset arts, andparticularly the reinforced composite arts, understand the concept ofpartial curing and how to determine conditions to partially cure a resinwithout undue experimentation. References herein to properties of the“cured composition” refer to a composition that is substantially fullycured. For example, the resin in a laminate formed from prepregs istypically substantially fully cured. One skilled in the thermoset artscan determine whether a sample is partially cured or substantially fullycured without undue experimentation. For example, one can analyze asample by differential scanning calorimetry to look for an exothermindicative of additional curing occurring during the analysis. A samplethat is partially cured will exhibit an exotherm. A sample that issubstantially fully cured will exhibit little or no exotherm. Partialcuring can be effected by subjecting the curable-composition-impregnatedreinforcing structure to a temperature of about 133 to about 140° C. forabout 4 to about 10 minutes.

Commercial-scale methods of forming composites are known in the art, andthe curable compositions described herein are readily adaptable toexisting processes and equipment. For example, prepregs are oftenproduced on treaters. The main components of a treater include feederrollers, a resin impregnation tank, a treater oven, and receiverrollers. The reinforcing structure (E-glass, for example) is usuallyrolled into a large spool. The spool is then put on the feeder rollersthat turn and slowly roll out the reinforcing structure. The reinforcingstructure then moves through the resin impregnation tank, which containsthe curable composition. The varnish impregnates the reinforcingstructure. After emerging from the tank, the coated reinforcingstructure moves upward through the vertical treater oven, which istypically at a temperature of about 175 to about 200° C., and thesolvent of the varnish is boiled away. The resin begins to polymerize atthis time. When the composite comes out of the tower it is sufficientlycured so that the web is not wet or tacky. The cure process, however, isstopped short of completion so that additional curing can occur whenlaminate is made. The web then rolls the prepreg onto a receiver roll.

While the above-described curing methods rely on thermal curing, it isalso possible to effect curing with radiation, including ultravioletlight and electron beams. Combinations of thermal curing and radiationcuring can also be used.

In some embodiments, a composite is formed by a method comprisingimpregnating a reinforcing structure with a curable composition;partially curing the curable composition to form a prepreg; andlaminating a plurality of prepregs; wherein the curable compositioncomprises a poly(arylene ether), a curing promoter, and optionally, anauxiliary epoxy resin; and wherein the poly(arylene ether) has thestructure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter, and the auxiliary epoxy resin are further describedabove.

In some embodiments, a printed circuit board comprises a compositeformed by a method comprising impregnating a reinforcing structure witha curable composition; partially curing the curable composition to forma prepreg; and laminating a plurality of prepregs; wherein the curablecomposition comprises a poly(arylene ether), a curing promoter, andoptionally, an auxiliary epoxy resin; and wherein the poly(aryleneether) has the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2. The poly(arylene ether), thecuring promoter, and the auxiliary epoxy resin are further describedabove.

The invention includes at least the following embodiments.

Embodiment 1

A poly(arylene ether) having the structure

R—W—R,

wherein W is a divalent poly(arylene ether) residue terminated withphenolic oxygen atoms, and R is an epoxybenzyl group having thestructure

wherein each occurrence of R is the same or different, and eachoccurrence of m is independently 1 or 2.

Embodiment 2

The poly(arylene ether) of embodiment 1, having the structure

wherein each occurrence of m is independently 1 or 2; Q¹ and Q² are eachindependently selected from the group consisting of halogen,unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl,C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂halohydrocarbyloxy wherein at least two carbon atoms separate thehalogen and oxygen atoms; each occurrence of Q³ and Q⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;x and y are independently 0 to about 30, provided that the sum of x andy is at least 2; and L has the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;z is 0 or 1; and Y has a structure selected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the groupconsisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶and R⁷ is independently selected from the group consisting of hydrogen,C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷collectively form a C₄-C₁₂ alkylene group.

Embodiment 3

The poly(arylene ether) of embodiment 1 or 2, wherein the epoxybenzylgroup is selected from the group consisting of

and a combination thereof.

Embodiment 4

A poly(arylene ether) having the structure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

Embodiment 5

A process of making the poly(arylene ether) of claim 1, comprisingreacting a peroxide-containing reagent with a vinylbenzyl-terminatedpoly(arylene ether).

Embodiment 6

The process of embodiment 5, wherein the vinylbenzyl-terminatedpoly(arylene ether) has the structure

wherein each occurrence of m is independently 1 or 2; Q¹ and Q² are eachindependently selected from the group consisting of halogen,unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl,C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂halohydrocarbyloxy wherein at least two carbon atoms separate thehalogen and oxygen atoms; each occurrence of Q³ and Q⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;x and y are independently 0 to about 30, provided that the sum of x andy is at least 2; and L has the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independentlyselected from the group consisting of hydrogen, halogen, unsubstitutedor substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxywherein at least two carbon atoms separate the halogen and oxygen atoms;z is 0 or 1; and Y has a structure selected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the groupconsisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶and R⁷ is independently selected from the group consisting of hydrogen,C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷collectively form a C₄-C₁₂ alkylene group.

Embodiment 7

The process of embodiment 5 or 6, wherein the peroxide-containingreagent is an aliphatic or aromatic peracid selected from the groupconsisting of perbenzoic acid, 3-chloroperbenzoic acid, monoperphthalicacid, p-methoxyperbenzoic acid, p-nitroperbenzoic acid,m-nitroperbenzoic acid, α-pernaphthoic acid, β-pernaphthoic acid,phenylperacetic acid, performic acid, peracetic acid, perpropionic acid,perbutyric acid perisovaleric acid, perheptanoic acid, and combinationsthereof.

Embodiment 8

The process of any of embodiments 5-7, further comprising reacting ahydroxyl terminated poly(arylene ether) with a vinylbenzyl halide in thepresence of an alkali metal alkoxide to form the vinylbenzyl-terminatedpoly(arylene ether), wherein the vinylbenzyl halide has the structure

wherein X is fluoride, chloride, bromide, or iodide, and m is 1 or 2;and wherein the hydroxyl-terminated poly(arylene ether) has thestructure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

Embodiment 9

The process of embodiment 8, wherein the vinylbenzyl halide is3-vinylbenzyl chloride, 4-vinylbenzyl chloride, or a combinationthereof.

Embodiment 10

A process of making a poly(arylene ether), comprising:

reacting a hydroxyl-terminated poly(arylene ether) having the structure

with 4-vinylbenzyl chloride to form a vinylbenzyl-terminatedpoly(arylene ether) having the structure

and reacting the vinylbenzyl-terminated poly(arylene ether) with aperacid to form an epoxybenzyl-terminated poly(arylene ether) having thestructure

wherein each occurrence of a and b is independently 0 to about 20,provided that the sum of a and b is at least 2.

Embodiment 11

A curable composition comprising the poly(arylene ether) of embodiment1, and a curing promoter.

Embodiment 12

The curable composition of embodiment 11, wherein the curing promotercomprises a hardener selected form the group consisting of amines,dicyandiamide, polyamides, amidoamines, Mannich bases, anhydrides,phenol-formaldehyde resins, carboxylic acid functional polyesters,polysulfides, polymercaptans, isocyanates, cyanate esters, andcombinations thereof.

Embodiment 13

The curable composition of embodiment 11 or 12, wherein the curingpromoter comprises an amine hardener, and wherein the poly(aryleneether) and the curing promoter provide a ratio of total epoxyequivalents to total amine equivalents of about 1:1 to about 1.3:1.

Embodiment 14

The curable composition of any of embodiments 11-13, wherein the curingpromoter comprises a hardener selected from the group consisting ofm-phenylenediamine, 4,4′-diaminodiphenylmethane, and combinationsthereof.

Embodiment 15

The curable composition of any of embodiments 11-14, further comprisingan auxiliary epoxy resin.

Embodiment 16

The curable composition of embodiment 15, wherein the auxiliary epoxyresin is selected from the group consisting of aliphatic epoxy resins,cycloaliphatic epoxy resins, bisphenol A epoxy resins, bisphenol-F epoxyresins, phenol novolac epoxy resins, cresol-novolac epoxy resins,biphenyl epoxy resins, polyfunctional epoxy resins, naphthalene epoxyresins, divinylbenzene dioxide, 2-glycidylphenylglycidyl ether,dicyclopentadiene-type epoxy resins, multi aromatic resin type epoxyresins, and combinations thereof.

Embodiment 17

The curable composition of embodiment 15 or 16, wherein the auxiliaryepoxy resin comprises a diglycidyl ether of2,2-bis(4-hydroxyphenyl)propane.

Embodiment 18

The curable composition of any of embodiments 15-17, wherein the curingpromoter comprises an amine hardener, and wherein the poly(aryleneether), the curing promoter, and the auxiliary epoxy resin provide aratio of total epoxy equivalents to total amine equivalents of about 1:1to about 1.3:1.

Embodiment 19

The curable composition of any of embodiments 11-18, comprising about 1to about 99.9 weight percent of the poly(arylene ether), and about 0.1to 50 weight percent of the curing promoter, based on the total weightof the curable composition.

Embodiment 20

The curable composition of embodiment 19, further comprising about 1 toabout 99 weight percent of an auxiliary epoxy resin, based on the totalweight of the curable composition.

Embodiment 21

The curable composition of embodiment 19, further comprising about 2 toabout 100 parts by weight of a solvent having an atmospheric boilingpoint of about 50 to about 250° C., based on 100 parts by weight totalof the poly(arylene ether) and the curing promoter.

Embodiment 22

The curable composition of embodiment 20, further comprising about 2 toabout 100 parts by weight of a solvent having an atmospheric boilingpoint of about 50 to about 250° C., based on 100 parts by weight totalof the poly(arylene ether), the curing promoter, and the auxiliary epoxyresin.

Embodiment 23

The curable composition of embodiment 19, further comprising about 2 toabout 900 parts by weight of an inorganic filler, based on 100 parts byweight total of the poly(arylene ether) and the curing promoter.

Embodiment 24

The curable composition of embodiment 20, further comprising about 2 toabout 900 parts by weight of an inorganic filler, based on 100 parts byweight total of the poly(arylene ether), the curing promoter, and theauxiliary epoxy resin.

Embodiment 25

A process of making the curable composition of embodiment 11, comprisingmixing the poly(arylene ether) and the curing promoter at about 10 toabout 200° C.

Embodiment 26

A process of making the curable composition of embodiment 15, comprisingmixing the poly(arylene ether), the curing promoter, and the auxiliaryepoxy resin at about 10 to about 200° C.

Embodiment 27

A cured composition obtained by curing the curable composition of any ofembodiments 11-14.

Embodiment 28

A cured composition obtained by curing the curable composition of any ofembodiments 15-18.

Embodiment 29

The cured composition of embodiment 28, exhibiting a single glasstransition temperature.

Embodiment 30

The cured composition of embodiment 28 or 29, having at least one of thefollowing properties: a glass transition temperature of about 150 toabout 200° C.; a dielectric constant of about 2.8 to about 3.2, asmeasured at 1,000 megahertz in accordance with IPC-TM-650 2.5.5.9; aloss tangent of about 0.011 to about 0.017, as measured at 1,000megahertz in accordance with IPC-TM-650 2.5.5.9; and a water absorptionof less than or equal to 2 weight percent, measured after immersion indeionized water at 80° C. for 250 hours.

Embodiment 31

The cured composition of any of embodiments 28-30, wherein a surface ofa microtomed slice of the cured composition is not etched by exposure totoluene at 23° C. for 15 seconds, as viewed under 3,000× magnificationby scanning electron microscopy.

Embodiment 32

An article comprising the cured composition of embodiment 27.

Embodiment 33

An article comprising the cured composition of embodiment 28.

Embodiment 34

A method of forming a composite, comprising: impregnating a reinforcingstructure with the curable composition of any of embodiments 11-24;partially curing the curable composition to form a prepreg; andlaminating a plurality of prepregs.

Embodiment 35

A composite formed by the method of embodiment 34.

Embodiment 36

A printed circuit board comprising a composite formed by the method ofembodiment 34.

The invention is further illustrated by the following non-limitingexamples.

Preparative Example 1

In a 500-milliliter three-neck flask equipped with a mechanical stirrerand nitrogen inlet tube, 90.0 grams of vinylbenzyl-terminatedpoly(arylene ether) (0.1125 moles of vinyl functionality) was dissolvedin 300 milliliters chloroform. An ice/water bath was used to cool thesolution to 0-5° C. Then 26.8 grams of 3-chloroperbenzoic acid (75%purity; 0.1165 moles) was added. The solution was stirred at 0-5° C. for7 hours. As the reaction proceeded, 3-chlorobenzoic acid (a by-product)precipitated from solution.

The solution was stored at 0° C. overnight. The next day, the3-chlorobenzoic acid precipitate was removed by centrifugation anddecantation. The resulting clear solution was combined with methanol toprecipitate the epoxybenzyl-terminated poly(arylene ether). The productwas dried in a vacuum oven at 60° C. and 25 inches of vacuum for 16hours. The weight of the product was 85 grams (approximately 95% yield).

The product was analyzed by proton nuclear magnetic resonance (¹H-NMR)spectroscopy using a Varian Mercury Plus 400 MHz ¹H-NMR spectrometer.Peak assignments for the labeled protons in the terminal groups for thestarting material and product indicated in the structures below aregiven Table 1.

TABLE 1 ¹H-NMR Chemical Shifts Vinylbenzyl-terminatedEpoxybenzyl-terminated Poly(arylene ether) Poly(arylene ether) ProtonNumber Chemical Shift Proton Number Chemical Shift 1 7.42 6 7.3 2 6.70,6.74 7 7.44 3 5.76 8 3.88 4 5.25 9 3.15 5 4 . . . 75 10 2.80, 2.79 — — 54.75

Examples 1-4 and Comparative Examples 1-4

Individual components used to prepare the cured compositions in theworking examples are summarized in Table 2. The chemical structures andacronyms of the raw materials listed in Table 2 are provided below.

The epoxybenzyl-terminated poly(arylene ether) used in Examples 1-4 wasthat of Preparative Example 1. As reported in Table 2, epoxy equivalentweight (EEW) is the weight of resin in grams that contains one mole ofepoxy groups. It is also the molecular weight of the resin divided bythe number of epoxy groups in one molecule of resin. Hydroxyl equivalentweight (HEW) is the weight of resin in grams that contains one mole ofhydroxyl groups. It is also the molecular weight of the resin divided bythe number of hydroxyl groups in one molecule of resin Amine hydrogenequivalent weight (AHEW) is the weight of resin in grams that containsone mole of active (replaceable) amine hydrogen atoms. It is also themolecular weight of the resin divided by the number of active aminehydrogen atoms in one molecule of resin. Each of these equivalentweights is expressed in units of grams/equivalent (g/equiv). Conditionsfor preparing and curing the curable compositions are described below inthe context of specific curable compositions.

TABLE 2 Raw Materials EEW¹ HEW² AHEW³ Name Full Name (g/equiv) (g/equiv)(g/equiv) DGEBA 2,2-Bis(4-hydroxyphenyl)propane- 173 — — epichlorohydrinpolymer (diglycidyl ether of bisphenol A) PPE-2Ep Epoxybenzyl-terminated784 — — poly(arylene ether) MPD m-phenylenediamine — — 27.04 MDA4,4′-diaminodiphenylmethane — — 49.57 PPE-2OH Hydroxyl-terminatedpoly(arylene ether) — 784 — ¹Epoxide equivalent weight. ²Hydroxylequivalent weight. ³Amine hydrogen equivalent weight.

Characterization of the Cured Compositions

Glass transition temperatures (T_(g)) were measured on a TA Instruments2920 M-DS. The thermal scans were from 30 to 250° C. under a nitrogenatmosphere with a heating rate of 20° C./min.

Samples for Scanning Electronic Microscopy (SEM) were cut to size,microtomed to obtain a fresh, flat surface for analysis, and etched intoluene at 23° C. for 15 seconds. Then the samples were coated withgold. The samples were examined using a Carl Zeiss AG-EVO® 40 Seriesscanning electron microscope. The conditions were SEM mode, a probecurrent of 40 picoamps, HV (high vacuum), and an acceleration voltage of20 kilovolts.

Dielectric constants and dissipation factors were measured at 23° C.according to IPC-TM-650 2.5.5.9. Test samples were in the shape ofrectangular prisms having dimensions of 5 centimeters by 5 centimetersby 3.5 millimeters. The samples were conditioned at 23° C. and 50%relative humidity for a minimum of 24 hours before testing. Themeasuring cell was a Hewlett-Packard Impedance Material Analyzer Model4291B and had a width of 27.5 centimeters, a height of 9.5 centimeters,and a depth of 20.5 centimeters. The electrodes were Hewlett-PackardModel 16453A and had a diameter of 7 millimeters. Measurements wereconducted using a capacitance method, sweeping a range of frequencieswhen DC voltage was applied to the dielectric materials. The appliedvoltage was 0 2 millivolt to 1 volt at the frequency range of 1megahertz to 1 gigahertz. Values for dielectric constants (Dk, relativepermittivity) and loss tangent (Df, dissipation factor) at frequenciesof 100 megahertz, 500 megahertz, and 1000 megahertz (1 gigahertz) wererecorded.

Comparative Example 1 Epoxy/m-Phenylenediamine

DGEBA (20.00 grams, 0.1156 equivalents) was heated to 80-100° C. and MPD(2.78 grams, 0.1028 equivalents) was added and dissolved. The solutionwas transferred to an aluminum pan and placed in an oven at 100° C.After 1 hour the temperature was increased to 190° C. After 3 hours at190° C., the oven was turned off and allowed to cool to ambienttemperature overnight. The casting exhibited a T_(g) of 194° C. Thedielectric constants and loss tangents are provided in Table 3.

Comparative Example 2 25.8 Weight Percent Hydroxyl-TerminatedPoly(Arylene Ether)/Epoxy/m-Phenylenediamine

DGEBA (14.86 grams, 0.08588 equivalents) was heated to 80-100° C. andPPE-2OH (5.94 grams, 0.00758 equivalents) was added. After the PPE-2OHwas dissolved in the DGEBA, MDA (2.22 grams, 0.08210 equivalents) wasadded and dissolved. The solution was transferred to an aluminum pan andplaced in an oven at 100° C. After 1 hour the temperature was increasedto 190° C. After 3 hours at 190° C., the oven was turned off and allowedto cool to ambient temperatures overnight. The casting exhibited twodistinct T_(g) values (155 and 186° C.). The dielectric constants andloss tangents are provided in Table 3.

Example 1 14.9 Weight Percent Epoxybenzyl-Terminated Poly(AryleneEther)/Epoxy/m-Phenylenediamine

DGEBA (17.02 grams, 0.09837 equivalents) was heated to 80-100° C. andPPE-2Ep (3.40 grams, 0.00434 equivalents) was added. After the PPE-2Epwas dissolved in the DGEBA, MPD (2.47 grams, 0.09135 equivalents) wasadded and dissolved. The solution was transferred to an aluminum pan andplaced in an oven at 100° C. After 1 hour the temperature was increasedto 190° C. After 3 hours at 190° C., the oven was turned off and allowedto cool to ambient temperature overnight. The casting exhibited a singleT_(g) of 193° C. The dielectric constants and loss tangents are providedin Table 3.

Example 2 25.8 Weight Percent Epoxybenzyl-Terminated Poly(AryleneEther)/Epoxy/m-Phenylenediamine

DGEBA (14.86 grams, 0.08588 equivalents) was heated to 80-100° C. andPPE-2Ep (5.94 grams, 0.00758 equivalents) was added. After the PPE-2Epwas dissolved in the DGEBA, MPD (2.22 grams, 0.08210 equivalents) wasadded and dissolved. The solution was transferred to an aluminum pan andplaced in an oven at 100° C. After 1 hour the temperature was increasedto 190° C. After 3 hours at 190° C., the oven was turned off and allowedto cool to ambient temperature overnight. The casting exhibited a T_(g)of 192° C. The dielectric constants and loss tangents are provided inTable 3.

Comparative Example 3 Epoxy/4,4′-Diaminodiphenylmethane

DGEBA (20.00 grams, 0.1156 equivalents) was heated to 80-100° C. and theMDA (5.19 grams, 0.1029 equivalents) was added and dissolved. Thesolution was transferred to an aluminum pan and placed in an oven at100° C. After 1 hour the temperature was increased to 190° C. After 3hours at 190° C., the oven was turned off and allowed to cool to ambienttemperature overnight. The casting exhibited a T_(g) of 159° C. Thedielectric constants and loss tangents are provided in Table 3.

Comparative Example 4 13.7 Weight Percent Hydroxyl-TerminatedPoly(Arylene Ether)/Epoxy/4,4′-Diaminodiphenylmethane

DGEBA (17.24 grams, 0.09965 equivalents) was heated to 80-100° C. andPPE-2OH (3.45 grams, 0.004398 equivalents) was added. After the PPE-2OHwas dissolved in the DGBDA, MDA (4.57 grams, 0.09219 equivalents) wasadded and dissolved. The solution was transfer to an aluminum pan andplaced in an oven at 100° C. After 1 hour the temperature was increasedto 190° C. After 3 hours at 190° C., the oven was turned off and allowedto cool to ambient temperature overnight. The casting exhibited twodistinct T_(g) values (146 and 162° C.). The dielectric constants andloss tangents are provided in Table 3.

Example 3 13.7 Weight Percent Epoxybenzyl-Terminated Poly(AryleneEther)/Epoxy/4,4′-Diaminodiphenylmethane

DGEBA (17.24 grams, 0.09965 equivalents) was heated to 80-100° C. andPPE-2Ep (3.45 grams, 0.004398 equivalents) was added. After the PPE-2Epwas dissolved in the epoxy, MDA (4.57 grams, 0.09219 equivalents) wasadded and dissolved. The solution was transferred to an aluminum pan andplaced in an oven at 100° C. After 1 hour the temperature was increasedto 190° C. After 3 hours at 190° C., the oven was turned off and allowedto cool to ambient temperature overnight. The casting exhibited a T_(g)of 167° C. The dielectric constants and loss tangents are provided inTable 3.

Example 4 24.2 Weight Percent Epoxybenzyl-Terminated Poly(AryleneEther)/Epoxy/4,4′-Diaminodiphenylmethane

DGEBA (15.02 grams, 0.08682 equivalents) was heated to 80-100° C. andthe PPE-2Ep (6.11 grams, 0.007796 equivalents) was added. After thePPE-2Ep was dissolved in the epoxy, MDA (4.16 grams, 0.08392equivalents) was added and dissolved. The solution was transferred to analuminum pan and placed in an oven at 100° C. After 1 hour thetemperature was increased to 190° C. After 3 hours at 190° C. the ovenwas turned off and allowed to cool to ambient temperature overnight. Thecasting exhibited a T_(g) of 170° C. The dielectric constants and losstangents are provided in Table 3.

TABLE 3 Properties of Cured Poly(arylene ether)/Epoxy/DiamineCompositions Dielectric Constant Loss Tangent T_(g) (° C.) 100 MHz 500MHz 1,000 MHz 100 MHz 500 MHz 1,000 MHz C. Ex. 1 194 3.124 3.075 3.0530.01682 0.01645 0.01601 C. Ex. 2 155, 186 3.027 2.984 2.965 0.014240.01402 0.01366 Ex. 1 193 3.061 3.013 2.994 0.01502 0.01472 0.01440 Ex.2 192 3.016 2.973 2.954 0.01375 0.01350 0.01327 C. Ex. 3 159 3.130 3.0813.057 0.01701 0.01665 0.01617 C. Ex. 4 146, 162 3.080 3.033 3.0100.01582 0.0156 0.01501 Ex. 3 167 3.074 3.026 3.004 0.01551 0.015200.01472 Ex. 4 170 3.032 2.987 2.967 0.01403 0.01373 0.01347

The two MPD-cured epoxy resin systems comprising epoxybenzyl-terminatedpoly(arylene ether) each exhibited a single, high T_(g) value (193 and192° C. for Examples 1 and 2, respectively). However, the MPD-curedepoxy resin system comprising hydroxyl-terminated poly(arylene ether)(Comparative Example 2) exhibited two distinct T_(g) values (155 and186° C.), and both T_(g) values are lower than the Tg of Example 2 (192°C.). These results indicate that at least a portion of thehydroxyl-terminated poly(arylene ether) is not covalently bonded to theepoxy matrix and instead exists as a separate phase in the curedcomposition, thus giving rise to the second T_(g) peak. Similarly, thetwo MDA-cured epoxy resin systems comprising epoxybenzyl-terminatedpoly(arylene ether) each exhibited a single, high T_(g) value (167 and170° C. for Examples 3 and 4, respectively). However, the MDA-curedepoxy resin system comprising hydroxyl-terminated poly(arylene ether)(Comparative Example 4) exhibited two distinct T_(g) values (146 and162° C.), and both T_(g) values are lower than the Tg of Example 3 (167°C.).

Example 5

SEM was used to assess the incorporation of PPE-2Ep and PPE-2OH into thediamine/epoxy matrices. The surfaces of microtomed samples were etchedin toluene for 15 seconds. Any unbound PPE-2OH or PPE-2Ep will besoluble in toluene, and therefore is expected to be removed from thesurface. The SEM images of samples comprising PPE-2OH are presented inFIGS. 1( a) and 2(a), which clearly show surface voids. On the otherhand, surface voids are not seen in the SEM images of samples comprisingPPE-2OH presented in FIGS. 1( b) and 2(b). The images were all obtainedat the same level of magnification—3000×. These results suggest thathydroxyl-terminated poly(arylene ether) is not covalently bonded to theepoxy matrix in the cured compositions, while epoxybenzyl-terminatedpoly(arylene ether) is covalently bonded. Thus epoxybenzyl-terminatedpoly(arylene ether) is a significant improvement overhydroxyl-terminated poly(arylene ether) in terms of solvent resistance.

Example 6

Unnotched impact strength was used to assess the incorporation ofPPE-2Ep and PPE-2OH into the epoxy/diamine matrices on toughness. Theresults are summarized in Table 4 below. Unnotched Izod impact strength,expressed in joules per meter (J/m), was measured at 23° C. with ahammer energy of 2 foot-pounds in accordance with ASTM D 4812-06,“Standard Test Method for Unnotched Cantilever Beam Impact Strength ofPlastics”. Reported values reflect an average of 5 specimens percomposition. As can be seen from the data, the impact strength ofinventive Example 3 is improved relative to the epoxy resin ofComparative Example 3 and to the mixture of epoxy resin and PPE-2OH ofComparative Example 4. This indicates the improved incorporation of thePPE-2Ep into the epoxy/diamine matrix for the inventive PPE-2Ep relativeto the comparative examples.

TABLE 4 Impact Strength of Cured Poly(arylene ether)/Epoxy/DiamineCompositions Impact Ex. Description Strength, J/m C. Ex. 3 DGEBA/MDA 425C. Ex. 4 13.7 Weight percent PPE-2OH/DGEBA/MDA 461 Ex. 3 13.7 Weightpercent PPE-2Ep/DGEBA/MDA 506

Example 7

Water absorption in polymers is known to have adverse effects ondimensional stability, T_(g), mechanical properties, and dielectricproperties. Poly(arylene ether)s do not contain any polar groups whichwould strongly hydrogen bond to water, and therefore exhibit very lowwater absorption Amine cured epoxy resins can contain high levels ofhydroxyl groups. A primary amine can generate two hydroxyl groups byreaction with two epoxy groups. Since hydroxyl groups and amine groupscan form hydrogen bonds with water, epoxy resins have a tendency toabsorb water.

Water absorption as a function of PPE-2Ep content was measured for curedPPE-2Ep/DGEBA/MDA compositions of Comparative Example 3 and Examples 3and 4 as a function of PPE-2Ep content by immersion of cured testsamples in deionized water at 80° C. The water absorption was determinedby removing the test samples periodically, weighing the test samples,and replacing them in the water. The results for Comparative Example 3,and Examples 3 and 4 are graphed in FIG. 3. As can be seen from FIG. 3,water absorption is reduced for the inventive compositions of Examples 3and 4, and the reduction in water absorption is greatest for Example 4,which has the highest PPE-2Ep content.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to make and use the invention. The patentable scope of the inventionis defined by the claims, and can include other examples that occur tothose skilled in the art. Such other examples are intended to be withinthe scope of the claims if they have structural elements that do notdiffer from the literal language of the claims, or if they includeequivalent structural elements with insubstantial differences from theliteral language of the claims.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other. Each rangedisclosed herein constitutes a disclosure of any point or sub-rangelying within the disclosed range.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. Further, it should further be noted that the terms “first,”“second,” and the like herein do not denote any order, quantity, orimportance, but rather are used to distinguish one element from another.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context (e.g., itincludes the degree of error associated with measurement of theparticular quantity).

1. A curable composition comprising: a poly(arylene ether) having the structure R—W—R, wherein W is a divalent poly(arylene ether) residue terminated with phenolic oxygen atoms, and R is an epoxybenzyl group having the structure

wherein each occurrence of R is the same or different, and each occurrence of m is independently 1 or 2; and a curing promoter.
 2. The curable composition of claim 1, wherein the poly(arylene ether) has the structure

wherein each occurrence of m is independently 1 or 2; Q¹ and Q² are each independently selected from the group consisting of halogen, unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; each occurrence of Q³ and Q⁴ is independently selected from the group consisting of hydrogen, halogen, unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; x and y are independently 0 to about 30, provided that the sum of x and y is at least 2; and L has the structure

wherein each occurrence of R¹ and R² and R³ and R⁴ is independently selected from the group consisting of hydrogen, halogen, unsubstituted or substituted C₁-C₁₂ primary or secondary hydrocarbyl, C₁-C₁₂ hydrocarbylthio, C₁-C₁₂ hydrocarbyloxy, and C₂-C₁₂ halohydrocarbyloxy wherein at least two carbon atoms separate the halogen and oxygen atoms; z is 0 or 1; and Y has a structure selected from the group consisting of

wherein each occurrence of R⁵ is independently selected from the group consisting of hydrogen and C₁-C₁₂ hydrocarbyl, and each occurrence of R⁶ and R⁷ is independently selected from the group consisting of hydrogen, C₁-C₁₂ hydrocarbyl, and C₁-C₆ hydrocarbylene wherein R⁶ and R⁷ collectively form a C₄-C₁₂ alkylene group.
 3. The curable composition of claim 1, wherein the poly(arylene ether) has the structure

wherein each occurrence of a and b is independently 0 to about 20, provided that the sum of a and b is at least
 2. 4. The curable composition of claim 1, wherein the curing promoter comprises a hardener selected form the group consisting of amines, dicyandiamide, polyamides, amidoamines, Mannich bases, anhydrides, phenol-formaldehyde resins, carboxylic acid functional polyesters, polysulfides, polymercaptans, isocyanates, cyanate esters, and combinations thereof.
 5. The curable composition of claim 1, wherein the curing promoter comprises an amine hardener, and wherein the poly(arylene ether) and the curing promoter provide a ratio of total epoxy equivalents to total amine equivalents of about 1:1 to about 1.3:1.
 6. The curable composition of claim 1, wherein the curing promoter comprises a hardener selected from the group consisting of m-phenylenediamine, 4,4′-diaminodiphenylmethane, and combinations thereof.
 7. The curable composition of claim 1, further comprising an auxiliary epoxy resin.
 8. The curable composition of claim 7, wherein the auxiliary epoxy resin is selected from the group consisting of aliphatic epoxy resins, cycloaliphatic epoxy resins, bisphenol A epoxy resins, bisphenol-F epoxy resins, phenol novolac epoxy resins, cresol-novolac epoxy resins, biphenyl epoxy resins, polyfunctional epoxy resins, naphthalene epoxy resins, divinylbenzene dioxide, 2-glycidylphenylglycidyl ether, dicyclopentadiene-type epoxy resins, multi aromatic resin type epoxy resins, and combinations thereof.
 9. The curable composition of claim 7, wherein the auxiliary epoxy resin comprises a diglycidyl ether of 2,2-bis(4-hydroxyphenyl)propane.
 10. The curable composition of claim 7, wherein the curing promoter comprises an amine hardener, and wherein the poly(arylene ether), the curing promoter, and the auxiliary epoxy resin provide a ratio of total epoxy equivalents to total amine equivalents of about 1:1 to about 1.3:1.
 11. The curable composition of claim 1, comprising about 1 to about 99.9 weight percent of the poly(arylene ether), and about 0.1 to 50 weight percent of the curing promoter, based on the total weight of the curable composition.
 12. The curable composition of claim 11, further comprising about 1 to about 99 weight percent of an auxiliary epoxy resin, based on the total weight of the curable composition.
 13. The curable composition of claim 11, further comprising about 2 to about 100 parts by weight of a solvent having an atmospheric boiling point of about 50 to about 250° C., based on 100 parts by weight total of the poly(arylene ether) and the curing promoter.
 14. The curable composition of claim 12, further comprising about 2 to about 100 parts by weight of a solvent having an atmospheric boiling point of about 50 to about 250° C., based on 100 parts by weight total of the poly(arylene ether), the curing promoter, and the auxiliary epoxy resin.
 15. The curable composition of claim 11, further comprising about 2 to about 900 parts by weight of an inorganic filler, based on 100 parts by weight total of the poly(arylene ether) and the curing promoter.
 16. The curable composition of claim 12, further comprising about 2 to about 900 parts by weight of an inorganic filler, based on 100 parts by weight total of the poly(arylene ether), the curing promoter, and the auxiliary epoxy resin.
 17. A cured composition obtained by curing the curable composition of claim
 1. 18. A cured composition obtained by curing the curable composition of claim
 7. 19. The cured composition of claim 18, exhibiting a single glass transition temperature.
 20. The cured composition of claim 18, having at least one of the following properties: a glass transition temperature of about 150 to about 200° C.; a dielectric constant of about 2.8 to about 3.2, as measured at 1,000 megahertz in accordance with IPC-TM-650 2.5.5.9; a loss tangent of about 0.011 to about 0.017, as measured at 1,000 megahertz in accordance with IPC-TM-650 2.5.5.9; and a water absorption of less than or equal to 2 weight percent, measured after immersion in deionized water at 80° C. for 250 hours.
 21. The cured composition of claim 18, wherein a surface of a microtomed slice of the cured composition is not etched by exposure to toluene at 23° C. for 15 seconds, as viewed under 3,000× magnification by scanning electron microscopy.
 22. An article comprising the cured composition of claim
 17. 23. An article comprising the cured composition of claim
 18. 24. A method of forming a composite, comprising impregnating a reinforcing structure with the curable composition of claim 1; partially curing the curable composition to form a prepreg; and laminating a plurality of prepregs.
 25. A composite formed by the method of claim
 24. 26. A printed circuit board comprising a composite formed by the method of claim
 24. 